Alan K. Osumi

Fast Spin-Echo, Magnetic Resonance Imaging-Measured Hippocampal Volume: Correlation with Neuronal Density in Anterior Temporal Lobectomy Patients

Summary: To assess the value of magnetic resonance imaging (MRI)‐measured hippocampal volume in the detection of hippocampal sclerosis, we studied 28 patients undergoing anterior temporal lobectomy for medically intractable mesial temporal lobe epilepsy. Hippocampal volumetry and visual analysis of T2 signal change were performed using fast spin‐echo T2‐weighted MRI. Quantitative neuronal density measurements were performed in the resected hippocampal specimens. There was a significant correlation between MRI‐measured absolute hippocampal volume (AHV) and neuronal density in CA1, CA2, and CA3 subfields (p<0. 0001, p < 0.01, and p < 0.05, respectively). Differential hippocampal volume (side‐to‐side volume difference) failed to detect bilateral atrophy in three patients, but the bilateral hippocampal atrophy was recognized by considering AHV in these patients. This study suggests that MRI‐measured AHV can be of value in evaluating patients with mesial temporal lobe epilepsy, especially when there is no side‐to‐side difference in hippocampal volumetry.

Meningioangiomatosis: CT and MR findings.

Meningioangiomatosis (MA) is a rare hamartomatous lesion of the cerebral cortex; to date only 18 cases with imaging findings have been reported in the English literature. The origin of MA is probably malformative, with possible association with neurofibromatosis. These lesions frequently cause seizures in young patients. We report two new cases seen at our institution and present their CT and MR findings clearly illustrating MA cortex infiltration. Gd-DTPA used in one of the two cases failed to cause enhancement.

MR findings in a patient with Ramsay-Hunt syndrome.

A case of Ramsay Hunt syndrome (herpes zoster oticus) was studied with Gd diethylenetriamine pentaacetic acid enhanced magnetic resonance imaging using a surface coil rather than a conventional head coil. This allowed us to demonstrate in detail the inflammatory changes of the multiple structures, involved.

Utility of MR imaging in pediatric spinal cord injury

We evaluated the utility of MR imaging in pediatric patients with acute and subacute spinal cord injuries. MR imaging of 22 pediatric patients with suspected traumatic spinal cord injuries was reviewed. MR findings were correlated with physical examination and compared to available radiographs and CT examinations performed at time of presentation. Twelve patients had abnormalities on MR imaging. Seven had spinal cord contusions; five contusions were hemorrhagic. Five of seven patients with cord contusion had normal radiographs and CT exams. Six patients with normal radiographs and CT examinations had abnormal MR studies revealing cord contusion, ligamentous injury, disc herniation, and epidural hematoma. MR is useful in initial evaluation of pediatric patients with spinal cord injuries and in prognosis of future neurologic function. In the setting of spinal cord symptomatology and negative radiographic studies, MR imaging should be performed. Surgically correctable causes of cord compression demonstrated by MR imaging include disc herniation, epidural hematoma, and retropulsed fracture fragments. The entity of spinal cord injury without radiographic abnormality is a diagnosis of exclusion which should only be made after radiologic investigation with radiographs, high-resolution thin-section CT, and MR imaging.

Post-traumatic epidermoid cyst: CT appearance

We report development of an intracranial epidermoid cyst 2 years after a depressed skull fracture. The epidermoid cyst is presumed to be the result of introduction of epidermal elements at the time of trauma. Post-traumatic intracranial epidermoid cysts are rare and appear to be less common than those occurring in the spine.